[release-12.1.2] CloudWatch: Use default region when query region is unset (#111079)

CloudWatch: Use default region when query region is unset (#109089)

CloudWatch: use default region when region is unset
(cherry picked from commit 5f4097a159)

Co-authored-by: Isabella Siu <Isabella.siu@grafana.com>

pkg/tsdb/cloudwatch/accounts_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/grafana/grafana-aws-sdk/pkg/awsauth"
+	"github.com/grafana/grafana-aws-sdk/pkg/awsds"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/log"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/resource/httpadapter"
 	"github.com/grafana/grafana/pkg/tsdb/cloudwatch/mocks"
@@ -23,6 +24,9 @@ func newTestDatasource(opts ...func(*DataSource)) *DataSource {
 		AWSConfigProvider: awsauth.NewFakeConfigProvider(false),
 		logger:            log.NewNullLogger(),
 		tagValueCache:     cache.New(0, 0),
+		Settings: models.CloudWatchSettings{
+			AWSDatasourceSettings: awsds.AWSDatasourceSettings{Region: "us-east-1"},
+		},
 	}
 	ds.resourceHandler = httpadapter.New(ds.newResourceMux())
 	for _, opt := range opts {

pkg/tsdb/cloudwatch/cloudwatch.go

@@ -59,7 +59,7 @@ type DataSource struct {
 }
 
 func (ds *DataSource) newAWSConfig(ctx context.Context, region string) (aws.Config, error) {
-	if region == defaultRegion {
+	if region == defaultRegion || region == "" {
 		if len(ds.Settings.Region) == 0 {
 			return aws.Config{}, models.ErrMissingRegion
 		}

pkg/tsdb/cloudwatch/cloudwatch_integration_test.go

@@ -269,6 +269,7 @@ func Test_CloudWatch_CallResource_Integration_Test(t *testing.T) {
 	t.Run("Should error for any request when a default region is not selected", func(t *testing.T) {
 		ds := newTestDatasource(func(ds *DataSource) {
 			ds.Settings.GrafanaSettings.ListMetricsPageLimit = 1000
+			ds.Settings.Region = ""
 		})
 
 		req := &backend.CallResourceRequest{